Method for transmitting data of different applications via packet transmission network, corresponding units and corresponding program

ABSTRACT

The invention relates, among other things, to a method, according to which data packets are forwarded in a packet transmission network ( 10 ), based on the routing data contained in said data packets. Depending on the type of application, when a transmission protocol is used, different values are used for a comparison variable, which determines a waiting time, in which the system waits for data packets that should arrive at a gateway ( 42 ) according to a predetermined sequence.

CLAIM FOR PRIORITY

[0001] This application claims priority to PCT/EPO1/13610, filed in theGerman language on Nov. 22, 2001, which claims the benefit to Germanapplication No. 00127455.2, filed in the German language on Dec. 14,2000.

TECHNICAL FIELD OF THE INVENTION

[0002] The invention relates to a method for transmitting data ofdifferent application, and in particular, in which data packets includerouting data and useful data, in a packet transmission network.

BACKGROUND OF THE INVENTION

[0003] The packet transmission network is, for example, the internet ora data transmission network operating according to an internet protocol.However other packet transmission networks are also used, for exampleATM networks (Asynchronous Transfer Mode). In an ATM network the datapackets are also referred to as cells. The data packets or cells containrouting data, which is used to forward the useful data contained in thedata packets, e.g. address data or path or channel details.

[0004] The data packets are transmitted on different transmission pathsand/or with different delay times via the packet transmission network.The sequence of the data packets must be reset in the receiver for manyapplications. For these purposes the data packets for example contain asequence number or a time stamp. Reference should be made in thiscontext for example to the RTP (Real Time Protocol) transmissionprotocol, which is stipulated in the defacto IETF (Internet EngineeringTask Force) standards RFC (Request for Comment) 1889 and RFC 1890. Theheader of an RTP data packet therefore contains a sequence number and atime stamp among other things, see RFC 1889, clause 5.1.A jitter bufferis used to effect a transmission with acceptable transmission timesdespite delays and data packet losses. Data packets are stored for aspecific time in the jitter buffer, until the system is no longerwaiting for an outstanding packet. If the jitter buffer is full,transmission continues even if individual data packets are missing or arepeat transmission is requested. The size of the jitter buffertherefore influences the waiting time for which the transmission isdelayed in the event of missing data packets.

[0005] Control of the size of the jitter buffer and therefore thewaiting time based on the capabilities of an encoder is known from thestandard H.323 “Packet based multimedia communications systems” from theITU-T (International Telecommunication Union—TelecommunicationStandardization Sector), clause 6.2.5.

SUMMARY OF THE INVENTION

[0006] The invention discloses a method for transmitting data ofdifferent applications via a packet transmission network, which inparticular ensures that delays in the transmission of the data packetsor data packet losses for different applications remain withinacceptable limits, without having an excessively detrimental effect onspecific applications. Corresponding units and a corresponding programshould also be specified.

[0007] In the invention, in addition to the method described above, thedata packets continue to be processed in the reset sequence based on acomparison variable, even if a previous data packet has not yet beenreceived. Alternatively repeat transmission of at least one data packetis requested based on the comparison variable. Also, different values ofthe comparison variable are predetermined for different applicationsdepending on the application for which the useful data is transmitted.The value for the comparison variable is expediently determined beforethe start of transmission of the data packets.

[0008] The invention allows the comparison variable to be tailored todifferent applications despite the use of a common transmissionprotocol. Predetermining the comparison variable based on the type ofapplication means that the comparison variable can be selected optimallyfor every application, without having to take account of otherapplications. For example for the real-time transmission of voice data acomparison variable is selected, which results in delays of maximum 30milliseconds due to waiting for a data packet. 30 milliseconds is stilltolerable for the transmission of voice data, without the voice qualitydropping below an acceptable value. For the transmission of data, thetransmission of which does not depend on real-time conditions, asignificantly higher value is selected for the comparison variable, forexample 250 milliseconds. This data is referred to hereafter as computerdata. The longer waiting time or larger buffer means that the error rateis smaller for the transmission of computer data than for thetransmission of voice data. The longer waiting time means it is alsopossible to process data packets which have a longer transmission time.

[0009] In one embodiment of the invention, the data packets each includea sequence number to stipulate the sequence and/or time details, showingthe relationship between the useful data included in the relevant datapackets and a reference time or reference clock. The measured data arecomparatively simple to allow resetting of the data packet sequence. Theuse of time details is particularly recommended when clocksynchronization is required at the receiver.

[0010] In another embodiment, the transmission protocol is a protocol,which is suitable for the real-time transmission of useful data.Real-time transmission means that the data is generated on thetransmission side and then has to be received by the receiver within aspecifically predetermined time period. In the case of voice data thetime period is 30 milliseconds, for example. A suitable protocol forreal-time transmission is the RTP protocol, which is stipulated in thedefacto standards RFC 1889 and 1890 referred to above. The RTP protocolis particularly suitable for the transmission of data packets via theinternet.

[0011] In another embodiment, one type of application is thetransmission of voice data in real time. The other type of applicationis the transmission of computer data, which is already stored in full ina transmission unit before the start of the transmission. Such computerdata is, for example, program data for specifying commands for aprocessor, text data, which specifies the wording of a text or imagedata, which specifies image elements of an image. But voice data, e.g. adictation, can also be computer data. The transmission protocol shouldtherefore be suitable for real-time transmission of data. However, thetransmission protocol that is suitable for the real-time transmission isalso used for the transmission of data, for which real-time transmissionmight not actually be necessary. As mentioned above, the use of only onetransmission protocol means a reduction in implementation costs. Also,the transmission protocol does not have to be changed every time thetype of application changes. The longer wait in the case of computerdata means that fewer requests are made for repeat transmission. The biterror rate for the transmission of computer data drops.

[0012] In another embodiment of the invention, a transmission path isestablished between two terminals of a circuit-switchedtelecommunication network for the transmission of useful data. A sectionof the transmission path between two gateways is located in the packettransmission network. The gateways are controlled by at least onecontrol unit. The control unit of the gateway receiving the data packetsor the control units of the gateways receiving the data packets in thecase of bi-directional transmission predetermine(s) the value of thecomparison variable.

[0013] The circuit-switched telecommunication network is for example anetwork in which the useful data is forwarded in time channels, e.g. intime channels of a PCM system (Pulse Code Modulation). Such a network isfor example the telephone network of Deutsche Telekom AG. The controlunit predetermines the value for the comparison variable, e.g. in aseparate control message. However messages used for other purposes mayalso be extended to include a field for transferring the value of thecomparison variable. The embodiment allows data of differentapplications to be transmitted easily even when circuit-switchedtelecommunication networks and packet transmission networks are shared.The advantages of the different networks can be better utilized in thisway.

[0014] In a subsequent embodiment the control unit is located at adistance from a gateway, e.g. at a distance of several 100 km. Astandard protocol or a defacto standard protocol is used between thecontrol unit and the gateway to transmit control messages. The protocolaccording to ITU-T standard H.248, the MGCP protocol (Media GatewayControl Protocol) is therefore used, see RFC 2705. The value of thecomparison variable is also transmitted taking into account theseprotocols or a protocol based on these protocols.

[0015] In still another embodiment, the control unit sends a connectionset-up message to the gateways receiving the data packets with theuseful data, specifying the value for the comparison variable. Thismeasure allows the value for the comparison variable to be transmittedwith a connection set-up message that had to be transmitted anyway.Additional messages are not required for transmitting the comparisonvariable. When using the MGCP protocol in one configuration thecomparison variable is designated by an identifier beginning with “X-”,which refers to what is known as an experimental parameter, see defactostandard RFC 2705, clause 3.2.2 “Parameter lines”, parameter “X-”. Anidentifier “X-MaJiBu” is therefore used to refer to the comparisonvariable in the nature of a meaningful name. The identifier is anacronym for the size of a maximum jitter buffer.

[0016] In a subsequent development at least one switching center of thecircuit-switched network is included in the stipulation of thetransmission path. The type of data application is determined using thevalue of a parameter stipulated in a signaling protocol for theswitching center. The parameter TMR (Transmission Medium Requirement)stipulated in the ISUP standard (ISDN user part) or in the BICC standardfor describing the requirement for the transmission medium can thereforebe used. The switching center then prompts predetermination of the valuefor the comparison variable based on the value of the parameter. Thetype of application can therefore be determined comparatively easily.The switching centers are involved anyway where necessary in setting upa transmission path so the cost of determining the type of applicationis marginal.

[0017] The core of the ISUP standard drawn up by the ITU-T(International Telecommunication Union—Telecommunication StandardizationSector) contains the following standards:

[0018] Q.761(21/99) “Signaling System No. 7—ISDN user part functionaldescription”,

[0019] Q.762 (2000) “Signaling System No. 7—ISDN user part generalfunction of messages and signals”,

[0020] Q.763 (1997) “Signaling System No. 7—ISDN user part formats andcodes”, and

[0021] Q.764 (09/97) “Signaling System No. 7—ISDN user part signalingprocedures”.

[0022] The parameter TMR referred to is therefore specified in Q.764,clause 2.1.1.1a. The values for the parameter TMR are stipulated in thestandard Q.763, clause 3.54. The value zero for example indicates voicedata. The value two indicates “64 kBit/s unrestricted” and refers forexample to the transmission of computer data.

[0023] The BICC standard is contained within the standard Q.1901 “BearerIndependent Call Control Protocol” drawn up by the ITU-T. The BICCstandard is based on the ISUP standard but is different from thisstandard. For example the central CIC (Circuit Identification Code) hasto be lengthened from two bytes to four bytes. At present the BICCstandard relates to the transmission of useful data in an ATM network.Extension to IP networks (Internet Protocol) is foreseeable.

[0024] The switching centers can also be used for connection set-up andconnection clearance. Signaling messages can also be exchanged betweengateways via the switching centers. A transport method stipulated forthe standards and with specific transport elements is used forexchanging these messages. Such a transport element is stipulated forexample in the standard Q.763 Add. 1 (06/00) and is designated there asan APP container (Application Transport Parameter). The transportprotocol for this container is determined in the standard Q.765 “RevisedRecommendation Q.765 (Application Transport Mechanism)”. The standardQ.765.5 “Application Transport Mechanism—Bearer Independent CallControl” is based on the standard Q.765 and was developed specificallyfor the BICC standard. However the transport elements specified in thestandard Q.765.5 can also be used when using the ISUP standard, inparticular when complying with the standards forming the core asspecified above.

[0025] In a different embodiment, the packet transmission network is theinternet or another data transmission network operating according tointernet protocol. Signaling between switching centers of thecircuit-switched network is executed according to the BICC standard oraccording to a slightly modified ISUP standard.

[0026] The invention also relates to a gateway, a control unit for agateway and a switching center. The said units are used to implement theinventive method and its developments. The technical effects referred toabove therefore also apply to these units.

[0027] The invention also relates to a program with a sequence ofcommands, during the execution of which the invention is executed by aprocessor or the function of one of the corresponding units is provided.The technical effects referred to above also apply to the program.

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Embodiments of the invention are described below using theattached drawings. These show:

[0029]FIG. 1 shows a telephone network connected to the internet andsignaling messages exchanged in the connected networks to establishtransmission paths.

[0030]FIG. 2 shows the structure of an information element fortransmitting an internet address.

[0031]FIG. 3 shows the structure of an information element fortransmitting an RTP port number.

[0032]FIG. 4 shows the structure of a code element for designating thecall instance.

[0033]FIG. 5 shows successive data packets and waiting times.

DETAILED DESCRIPTION OF THE INVENTION

[0034]FIG. 1 shows a telephone network 12 connected to the internet 10,e.g. the Deutsche Telekom AG telephone network. FIG. 1 shows two parts14 and 16 of the telephone network 12. The part 14 is located forexample in South Germany and the part 16 in North Germany. A terminalswitching center 18 is shown in the part 14, to which a datatransmission computer DA of a subscriber TlnA is connected via atransmission line 20, e.g. via an ISDN connection (Integrated ServicesDigital Network). The terminal switching center 18 is connected via aninter-exchange line 22 to a transit switching center 24. The transitswitching center 24 is for example a conventional EWSD-type (digitalelectronic switching system) switching center from Siemens AG. Atransmission route 26 goes from the transit switching center 24 to agateway 28. The transmission route 26 is for example a channel of aPCM-30 system (Pulse Code Modulation), as used for the transmission ofvoice data between different switching centers. The PCM method uses theITU-T CODEC G.711. The connections between different switching centersare also referred to as trunks. The function of the gateway 28 isdescribed in more detail below.

[0035] The part 16 of the telephone network 12 includes a transitswitching center 34, e.g. of the EWSD type. The transit switching center34 is connected via an inter-exchange line 36 to a terminal switchingcenter 38, to which the data transmission computer DB of a subscriberTlnB is connected. A transmission route 40 goes from the transitswitching center 34 to a gateway 42. The transmission route 40 is forexample a PCM channel as is usually used to transmit voice data betweenswitching centers. The function of the gateway 42 is described in moredetail below.

[0036] The telephone network 12 also includes two switching centers 48and 50, which are developments of the EWSD-type switching centers. Inaddition to the functions of an EWSD-type switching center, theswitching centers 48 and 50 also carry out the functions of serviceprovision computers 52 and 54. These additional functions are alsodescribed in more detail below using FIG. 1. A signaling connection 56can be set up between the switching center 58 and the transit switchingcenter 24 and this is used to transmit signaling messages according tothe IUSP (ISDN User Part) protocol. Examples of messages of thisprotocol are described below using FIG. 1.

[0037] A signaling connection 58 can be set up between the switchingcenters 48 and 50. Signaling messages via this signaling connection arealso transmitted according to the ISUP protocol. Information elementsare transmitted as a component of the signaling messages in an APP(Application Association Parameter) container according to standardQ.765 Add. 1 (06/00). These information elements are described belowusing FIGS. 2 and 3.

[0038] A signaling connection 60 can be set up between the switchingcenter 50 and the transit switching center 34 and this is used totransmit signaling messages according to the ISUP protocol.

[0039] Both the telephone network 12 and the internet 10 are used totransmit voice data between the subscriber TlnA and the subscriber TlnBor computer data between the computers DA and DB. Voice data or computerdata is transmitted circuit-switched in voice channels within thetelephone network 12. However voice data or computer data is transmittedin data packets within the internet 10.

[0040] In the gateways 28 and 42 voice data or computer data received ineach of the voice channels is divided into data packets and forwardedinto the internet 10. Data packets with voice data or computer datacoming from the internet 10 are unpacked in the gateways 28 and 42 andforwarded in voice channels into the telephone network 12. The gateway28 or 42 is connected via a transmission route 64 or 66 to the internet10. This means that data packets can be exchanged via the internet 10between the gateways 28 and 42. The service provision computers 52 and54 are also connected to the internet 10. Data packets can thereforealso be exchanged between the service provision computers 52 or 54 andthe gateways 28 and 42, see signaling path 72 between the serviceprovision computer 52 and the gateway 28 or signaling path 74 betweenthe service provision computer 54 and the gateway 42. The gateways 28and 42 and the service provision computers 52 and 54 each have at leastone internet address, at which they are accessible in the internet 10.

[0041] Signaling messages for setting up a connection for transmittingcomputer data or voice data between the subscriber TlnA and thesubscriber TlnB are described below. When a call connection is being setup between the subscriber TlnA and the subscriber TlnB or a datatransmission connection is being set up between the computers DA and DB,the transit switching center 24 generates a connection set-up message100, also referred to as an IAM message (Initial Address Message) attime t1 according to the ISUP protocol. This message includes, amongother things for example, the full call number of the subscriber TlnB inthe telephone network 12 and the number of a time slot on thetransmission route 26 to be used for the transmission. The type ofconnection and therefore also the type of application is indicated in aparameter of the connection set-up message 100 referred to as a TMR. Avalue for “voice connection” is indicated for voice data. A value for“64 kBit/s unrestricted” is indicated for data transmission betweencomputers, see standard Q.764, clause 2.1.1.1a.

[0042] The connection set-up message 100 is transmitted via thesignaling connection 56. When the connection set-up message 100 has beenreceived, a program is executed in the switching center 48, during theexecution of which it is ascertained that the internet 10 can be usedfor the transmission of the computer data or voice data. It isdetermined that the gateway 28 has to be used as the interface betweenthe telephone network 12 and the internet 10 on the side of thesubscriber TlnA. The service provision computer 52 is prompted by acontrol unit in the switching center 48 to execute the necessary stagesfor this. The value of the parameter TMR is forwarded according toprotocol to the service provision computer 52.

[0043] At a time t2 after the time t1 the service provision computer 52sends a connection set-up message 102 according to defacto standard RFC2705 to the gateway 28 via the signaling path 72. The connection set-upmessage 102 is also referred to as a CRCX message (Create Connection).The time slot to be used for the useful data transmission is indicatedin the connection set-up message 102. Also the method according to ITU-Tstandard G.723.1 for the transmission of voice data is indicated basedon the value in the parameter TMR as a CODEC (coding/decoding) for thetransmission of voice data, so that the voice data is compressed in thegateway 28. Where necessary voice pause suppression and echo suppressioncan be enabled for the transmission of voice data.

[0044] However the CODEC according to ITU-T standard G.711 is used forthe transmission of computer data, i.e. compression is not used. Voicepause suppression and echo suppression are disabled for the transmissionof computer data.

[0045] A value for a waiting time T is also indicated in a data field“X-MaJiBu” of the connection set-up message 102 and this is describedbelow using FIG. 5. 30 ms waiting time is selected for the transmissionof voice data and 200 ms for the transmission of computer data. The datafield “X-MaJiBu” was stipulated in what is referred to as an“experimental parameter”, see RFC 2705, clause 3.2.2 “Parameter lines”,example “X-FlowerOfTheDay: Daisy”.

[0046] When the parameter “X-MaJiBu” is indicated, the automatic settingof the size of what is referred to as a jitter buffer is disabled, asthis would influence the waiting time T. Automatic setting is onlyenabled if the parameter “X-MaJiBu” is not indicated in a connectionset-up message.

[0047] The gateway 28 processes the connection set-up message 102, setsthe necessary settings and generates a response message 104 in responseat a time t3. The response message 104 on the one hand confirms receiptof the connection set-up message 102 and contains among other things aninternet address and a port number, which can be used for the receipt ofuseful data for an RTP (Real Time Protocol, see RFC 1889 and RFC 1890)connection to be set up between the gateway 28 and the gateway 42 andwhich is now assigned to the time slot which is used on the transmissionroute 26 for the connection to be set up. The RTP connection is suitablefor transmitting voice data or computer data.

[0048] The service provision computer 52 receives the response message104 and forwards the received internet address and the port number tothe control unit of the switching center 48. The control unit of theswitching center 48 processes the connection set-up message 100according to the ISUP protocol and generates a connection set-up message106 at a time t4. The connection set-up message 106 is also referred toas an IAM message (Initial Address Message) according to the ISUPprotocol. The connection set-up message 106 contains two informationelements described in more detail below using FIGS. 2 and 3, in whichthe internet address and port number are forwarded, see points 107.These information elements are not stipulated in the ISUP standard butare transmitted via the signaling connection 58 in compliance with theISUP standard. The connection message 106 also contains the parameterTMR, with the same value as in the connection set-up message 100.

[0049] The switching center 50 receives the connection set-up message106 and also processes the information elements included in it. It isidentified from the content of these information elements or from thecode (CIC—Circuit Identification Code) for designating the call instancethat a telephone connection using the internet 10 is to be set up, not astandard telephone connection. The gateway 42 is identified by theswitching center 50 as the gateway to be used on the side of thesubscriber TlnB. The switching center 50 also determines a time slot, tobe used for the circuit-switched transmission of useful data between theswitching centers 50 and 34. This time slot designates a transmissionchannel of the transmission route 40. The switching center 50 alsoanalyzes the parameter TMR and reports this value to the serviceprovision computer 54.

[0050] The service provision computer 54 is prompted by the control unitof the switching center 50 to set up an internet connection via thesignaling path 74. At a time t5 the service provision computer 54 sendsa connection set-up message 108 to the gateway 42. The connection set-upmessage 108 corresponds to the defacto standard RFC 2705 referred toabove and is also referred to as a CRCX message (Create Connection). Themessage 108 includes the internet address and port number sent from thegateway 28 via the switching center 48, which are to be used for the RTPconnection to be set up. The time slot identified by the switchingcenter 50 is also included in the connection set-up message 108 as isthe CODEC based on the value of the parameter TMR, in the case of voiceconnections the CODEC G.723.1 and in the case of data transmissionconnections the CODEC G.711. In the case of voice connections voicepause suppression and echo suppression are automatically enabled in thegateway 42 using the connection set-up message 108. Data fields forsignaling these settings are stipulated according to defacto standardRFC 2705 for the message CRCX. In the case of data transmissionconnections voice pause suppression and echo suppression are howeverdisabled.

[0051] The connection set-up message 108 also includes a value for awaiting time T in a data field “X-MaJiBu”. The data field “X-MaJiBu” is,as stated above, a proprietary extension of the defacto standard RFC2705. A value for 30 ms waiting time is indicated for the transmissionof voice data. A value of 200 ms is selected for the transmission ofcomputer data.

[0052] During the processing of the connection set-up message 108 in thegateway 42, an internet address and an as yet unused port number of thegateway 42 are identified in the indicated time slot and these can beused for receipt of the useful data packets from the gateway 28. Echosuppression and voice pause suppression are enabled or disabled. Thevalue for the waiting time T is recorded.

[0053] Automatic setting of what is known as the jitter buffer, whichwould influence the waiting time T, is disabled. The gateway 42 thensends a response message 110 at a time t6 to confirm receipt of theconnection set-up message 108. The response message 110 also includesthe identified internet address of the gateway 42 and the identifiedport number.

[0054] The remainder of the connection set-up message 106 is processedin the switching center 50 according to the ISUP protocol. In thisprocess a connection set-up message 112 is generated, which istransmitted via the signaling connection 60 to the transit switchingcenter 34. The connection set-up message 112 is also referred to as anIAM message (Initial Address Message). The connection set-up message 112includes among other things the call number of the subscriber TlnB andthe time slot predetermined by the switching center 50. The connectionset-up message 112 is processed according to protocol in the transitswitching center 34 and forwarded to the terminal switching center 38.The terminal switching center 38 calls the subscriber TlnB or thecomputer DB.

[0055] During processing of the connection set-up message 106 afterreceipt of the response message 110 a transport message 114 is generatedin the switching center 50 and this is also referred to according to theISUP protocol as an APM message (Application Transport Message). Thetransport message 114 includes one information element with the internetaddress of the gateway 42 and one information element with the portnumber communicated by the gateway 42, see points 115. These informationelements have the same structure as the information elements describedbelow using FIGS. 2 and 3. The transport message 114 is transmitted tothe switching center 48 at a time t8.

[0056] The control unit of the switching center 48 extracts the internetaddress and port number from the transport message 114 and prompts theservice provision computer 52 to forward these connection parameters tothe gateway 28. The service provision computer 52 also sends a changemessage 116 according to defacto standard RFC 2705 at a time t9. Thechange message 116 is also referred to as an MDCX message (ModifyConnection). The change message 116 contains the internet address of thegateway 42 and the port number of the gateway 42 to be used for the RTPconnection to be set up.

[0057] The change message 116 is processed in the gateway 28 so that adirect transmission path 118 can be used for transmitting useful dataaccording to protocol RTP and CODEC G.711 or G.723.1 between thegateways 28 and 42. A response message generated by the gateway 28 inresponse to the change message 116 is not shown in FIG. 1.

[0058] At a subsequent time t10 the transit switching center 34generates a message 120 according to protocol, the message also beingreferred to as an ACM message (Address Complete Message), and signalsthat the dial numbers have been transmitted to connect subscribers TlnAand TlnB or computers DA and DB. The message 120 is processed accordingto protocol by the control unit of the switching center 50. At a timet11 the switching center 50 sends an ACM message 122 to the switchingcenter 48 according to the ISUP protocol. The switching center 48processes the ACM message 122 and in turn sends an ACM message 124 tothe transit switching center 24.

[0059] Let it be assumed that the parameter TMR has the value “64 kBit/sunrestricted”. If the computer DB of the subscriber TlnB logs on, thisis signaled according to the ISUP protocol to the transit switchingcenter 34. The transit switching center 34 generates a response message126 at a time t13 and this is transmitted via the signaling connection60 to the switching center 50. The response message 126 is also referredto as an ANM message (Answer Message). Charging starts on the basis ofthis message.

[0060] The response message 126 is processed according to protocol inthe switching center 50. During this process a response message 128 issent to the switching center 48. The switching center 48 generates aresponse message 130 to the transit switching center 24 based on theresponse message 128 at a time t15.

[0061] The data coming from the computer DA of the subscriber TlnA istransmitted in the parts 14 and 16 of the telephone network 12 and viathe transmission routes 26 and 40 in time slots and according to CODECG.711. Echo suppression, voice pause suppression and compression are notexecuted. The data is transmitted in data packets in the internet 10.Processes in the gateway 42 are described below using FIG. 5.

[0062]FIG. 2 shows the structure of an information element 150 fortransmitting an internet address. In a first embodiment the informationelement 150 contains nine successive data fields 152 to 168, each ofwhich has a length of 8 bits, i.e. one byte. Bit positions 0 to 7 are inthis sequence from right to left. An identifier is transmitted in thedata field 152 to identify the information element 150. The identifierhas the value 3, which is used in the standard Q.765.5 to refer to whatis known as an “Interworking Function Address” and which here shows thatthe information element 150 is used to transmit an internet address.

[0063] In a data field 154 the length of the information element 150 isspecified minus the data fields 152 and 154. In the embodiment the valueseven in stored in binary mode in the data field 154, see also standardQ.765.5, clause 11.1.1.

[0064] Compatibility information is transmitted in the data field 156,the value of which shows the recipient what should be done if it is notpossible to process the information element 150 fully, see also standardQ.765.5, clause 11.1.1.

[0065] In the data field 158 an authorization and format identifier istransmitted, which has the value “35” in hexadecimal notation. Thisvalue is used according to ITU standard X.213 Annex A as reference tothe internet protocol.

[0066] In the data field 160 an identifier with the value one is stored,when an internet address is transmitted according to internet protocolversion 4. The four bytes of the internet address are then transmittedin the adjacent data fields 162 to 168 according to version 4 of theinternet protocol.

[0067] If, on the other hand, an internet address is to be transmittedaccording to internet protocol version 6 using the information element150, there is a difference in the length details, see data field 154 anda difference in the data field 160. In the data field 160 the value zerois transmitted during transmission of internet addresses according tointernet protocol version 6. In this case, sixteen data fields 162 to170 are adjacent to the data field 160, with the 16 bytes of theinternet address stored in these according to internet protocol version6, see also points 172.

[0068]FIG. 3 shows the structure of an information element 180 fortransmitting a port number. The information element 180 includes fourdata fields 182 to 188, each with a length of one byte. The significanceof the data fields 182 to 186 corresponds in this sequence to thesignificance of the data fields 152 to 156 of the information element150. The value two is transmitted in the data field 182 to identify theinformation element 180 as the information element for transmitting aport number. The identifier transmitted in the data field 182 isreferred to as a “backbone network connection identifier” contrary tothe function provided here in the standard Q.765.5. The value two istransmitted in a data field 184 as the length of the information element180 minus the data fields 182 and 184. Information on compatibility istransmitted in the data field 186. The port number to be transmitted isthen transmitted in the data field 188, for example the port number tobe used for the RTP connection in the gateway 28 or in the gateway 42,see FIG. 1.

[0069]FIG. 4 shows the structure of a code element 200, which is used todesignate call instances between the switching centers 48 and 50. Thestructure of the code element 200 is stipulated in the standard Q.763,clause 1.2. The code element 200 includes two data fields 202 and 204,each of which has a length of one byte. The number of the instance istransmitted starting with the lowest value bit in the data field 202,see bit position 0, to bit position 7 of the data field 202 and thenonwards between bit positions 0 to 3 of the data field 204. Bitpositions 4 to 7 of the data field 204 are not used to designate theinstance. The code element 200 has no further data fields.

[0070]FIG. 5 shows three data packets 250, 252 and 254, which are sentin this sequence from the gateway 28 to the internet 10, to transmitcomputer data to the computer DB of the subscriber TlnB. The data packet250 contains a sequence number SN with the value one. A sequence numberSN with the value 2 or 3 is indicated in the data packet 252 or the datapacket 254. The sequence number is stipulated in the defacto standardRFC 1889.

[0071] The value in the data field “X-MaJiBu” in the connection set-upmessage 108 means that a waiting time T of 200 milliseconds has beenselected in the parameter TMR based on the value “64 kBit/sunrestricted” characterizing a data transmission.

[0072] The data packet 250 is received in the gateway 42 at a time t0 a.Starting from this time t0 a the system waits 200 milliseconds for thearrival of the data packet 252. Let it be assumed that the data packet252 does not arrive within this time period, see brackets 256. Afterexpiry of the waiting time T of 200 milliseconds the gateway 42 requeststhe repeat transmission of the data packet 252. If the data packet 252 athen arrives at a time t1 a, the gateway 42 resets the sequenceaccording to the sequence number SN. The forwarding of the useful datathen continues in the time channel of the transmission route 40. At atime t2 a the data packet 254 arrives in the gateway 42. The waitingtime T until the arrival of the fourth data packet is again 200milliseconds.

[0073] If voice data is transmitted from the subscriber TlnA to thesubscriber TlnB, the value “voice data” in the parameter TMR means that30 milliseconds is selected as the waiting time T. If the currentlyawaited data packet of the sequence does not arrive after this time,filler data is forwarded for example via the transmission route. Thenext data packet is then processed according to the sequence.

[0074] Similar processes to those described using FIG. 5 take place inthe gateway 28 for the counter direction. A waiting time T of 200milliseconds is also deployed during the transfer of the computer datareceived via the internet 10 to the time channel of the transmissionroute 26.

[0075] In another, embodiment signaling messages according to the BICCstandard are used to signal between the switching centers 48 and 50.Otherwise the processes described using FIGS. 1 to 5 remain unchanged.

[0076] In a further embodiment the value of the parameter “X-MaJiBu”directly determines the size of a buffer for storing the data packets inthe gateways. This indirectly determines the waiting time, as processinghas to continue when the buffer overflows.

[0077] The components specified in the embodiments are for examplecomponents of the SIEMENS AG SURPASS system, see the websitewww.siemens.com/data&voice. The service provision computers aretherefore components of the hiQ component of the SURPASS system.

[0078] IAM mit TMR=IAM with TMR

[0079] Daten DA=data DA

[0080] Daten DB=data DB

[0081]FIG. 1

[0082]FIG. 2

[0083] ID

[0084] Length

[0085] Comp.

[0086]FIG. 3

[0087] ID

[0088] Length

[0089] Comp.

[0090] RTP port

[0091]FIG. 4

[0092]FIG. 5

[0093] T=200 ms (data)

1. Method for transmitting data of different applications via a packettransmission network (10), in which data packets (250 to 254) containrouting data and useful data in a packet transmission network (10), inwhich the data packets (250 to 254) are forwarded based on the routingdata in the packet transmission network (10) and transmitted accordingto a predetermined transmission protocol, in which on receipt of thedata packets (250 to 256) the sequence is reset, in which the datapackets (250 to 254) are sent, in which the received data packets (250to 254) are further processed according to the sequence, in which theprocessing of the data packets (250 to 254) is continued in the resetsequence based on a comparison variable (“X-MaJiBu”), even if a previousdata packet (252) has not yet been received, or in which a repeattransmission of at least one data packet (252) is requested based on thecomparison variable (“X-MaJiBu”), and in which different values of thecomparison variable (“X-MaJiBu”) are predetermined for differentapplications depending on the application for which the useful data istransmitted.
 2. Method according to claim 1, characterized in that thedata packets (250 to 254) each contain a sequence number (SN) fordetermining the sequence and/or time details, indicating therelationship between the useful data contained in the relevant datapacket (250 to 254) and a reference time or a reference clock.
 3. Methodaccording to claim 1 or 2, characterized in that the transmissionprotocol is a protocol which is suitable for the real-time transmissionof useful data, preferably the RTP protocol.
 4. Method according to oneof the preceding claims, characterized in that one type of applicationis the real-time transmission of voice data and that the other type ofapplication is the transmission of computer data, which is alreadystored in full in a transmission unit (DA) before the start oftransmission, preferably program data for specifying commands for aprocessor and/or text data and/or image data, and/or that the value ofthe comparison variable for the transmission of computer data issignificantly higher than the value of the comparison variable for thetransmission of voice data.
 5. Method according to one of the precedingclaims, characterized in that a transmission path for transmittinguseful data is established between two terminals (DA, DB) of acircuit-switched telecommunication network (12), a section (118) of thetransmission path between two gateways (28, 42) is located in the packettransmission network (10), the gateways (28, 42) are controlled by atleast one control unit (52, 54), and that the control unit (54) of thegateway (42) receiving the data packets (250 to 252) predetermines thevalue of the comparison variable (“X-MaJiBu”).
 6. Method according toclaim 5, characterized in that a control unit (52, 54) is located at adistance from a gateway (28, 42), and that a standard protocol or adefacto standard protocol is used to transmit control messages betweencontrol unit (52, 54) and gateway (28, 42), in particular the protocolaccording to standard H.248 or the MGCP protocol or a protocol based onone of these protocols.
 7. Method according to claim 5 or 6,characterized in that the control unit (52, 54) sends a connectionset-up message (102, 108) to the gateway (28, 42) receiving the datapackets (250 to 254), in which connection set-up message (102, 108) thevalue for the comparison variable (“X-MaJiBu”) is indicated, and thatthe comparison variable (“X-MaJiBu”) is preferably stipulated in apacket.
 8. Method according to one of the preceding claims,characterized in that when determining the transmission path at leastone switching center (48, 50) is used to switch data in acircuit-switched data transmission network, and that the type of dataapplication is identified using a parameter stipulated in a signalingprotocol for switching centers, preferably using the parameter (TMR)stipulated in the ISUP standard or in the BICC standard for describingthe request to the transmission medium, and that the switching center(48, 50) prompts the predetermination of the value for the comparisonvariable (“X-MaJiBu”).
 9. Method according to one of the precedingclaims, characterized in that the packet transmission network (10) isthe internet or another data transmission network operating according tothe internet protocol.
 10. Method according to one of the precedingclaims, characterized in that the value of the comparison variabledirectly indicates a waiting time or that the value of the comparisonvariable determines the size of a buffer for storing data packets. 11.Gateway (28, 42), characterized in that the gateway (28, 42) isstructured so that it is suitable for use in a method according to oneof claims 1 to
 10. 12. Control unit (52, 54) for a gateway (28, 42),characterized in that the control unit (52, 54) is structured so that itis suitable for use in a method according to one of claims 1 to
 10. 13.Switching center (48, 50), characterized in that the switching center(48, 50) contains a control unit (52, 54) according to claim
 12. 14.Program with a command sequence, during the execution of which a methodaccording to one of claims 1 to 10 is executed by a processor or thefunction of a unit is provided according to one of claims 11 to 13.